• 제목/요약/키워드: contraction nozzle

검색결과 36건 처리시간 0.028초

노즐 수축각이 SNECMA 노즐목 가변 추력기 성능에 미치는 영향 (Effect of Nozzle Contraction Angle on Performance of the SNECMA Modulatable Thrust Devices)

  • 왕승원;허환일
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2011년도 제37회 추계학술대회논문집
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    • pp.14-17
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    • 2011
  • 본 연구에서는 노즐 수축각의 차이에 따라 추력기의 성능에 어떤 영향을 미치는지 알아보기 위해 SNECMA 노즐목 가변 추력기에 대해서 4가지 다른 노즐 수축각을 사용하여 수치해석을 수행하였다. 공력하중과 추력성능에 대해 분석하였고 노즐 수축각 $83^{\circ}$의 모델이 가장 좋은 결과를 보였다.

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Effect of Suction Nozzle Modification on the Performance and Aero-acoustic Noise of a Vacuum Cleaner

  • Park, Cheol-Woo;Lee, Sang-Ik;Lee, Sang-Joon
    • Journal of Mechanical Science and Technology
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    • 제18권9호
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    • pp.1648-1660
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    • 2004
  • The suction nozzle of a vacuum cleaner was modified to enhance the power performance and to reduce the airflow-induced acoustic noise. The suction power efficiencies of the vacuum cleaner were measured for various nozzles; (1) original nozzle, (2) original nozzle with modified trench height, (3) original nozzle with modified connecting chamber, and (4) a combination of (2) and (3). In addition, the suction pressure and sound pressure level around the suction nozzle were measured to validate the reduction of acoustic noise. The power efficiency and mean suction pressure increased when the trench height of the suction nozzle was increased. This was attributed to the suppression of the flow separation in the suction channel. Modification of the connecting chamber in the original nozzle, which had an abrupt contraction from a rectangular chamber into a circular pipe, into a smooth converging contraction substantially improved the suction flow into the connecting pipe. When both modifications were applied simultaneously, the resulting suction nozzle was more effective from the viewpoints of aerodynamic power increase and sound pressure level reduction.

원형단면 노즐의 급확대 축소부를 통한 유동손실에 대한 연구 (A Study on the Flow Loss for Sudden Expansion and Contraction Part of Circular Pipe Nozzle)

  • 고영하
    • Journal of Advanced Marine Engineering and Technology
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    • 제24권6호
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    • pp.89-95
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    • 2000
  • To obtain an exact flow loss in piping systems is very important in the face of efficiency anticipation and work control of plant. The object of this study is to get the flow loss through the experiment for sudden expansion and contraction part of circular pipe nozzle. The experiment in this study is performed after getting the flow loss factor for sudden expansion and contraction through preliminary experiments. It is confirmed that the results of this study agreed with the approximated equation of Ikeda and Matsuo. It is proved that flow loss factor ${\zeta}_3$for sudden expansion and contraction part of circular pipe is dependent on $L/D_1$in these experimental conditions.

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끝벽의 형상이 터빈 노즐안내깃 캐스케이드내 3차원 유동에 미치는 영향에 관한 연구 (Experimental Study on Effect of the Contoured Endwall on the Three-Dimensional Flow in a Turbine Nozzle Guide Vane Cascade)

  • 윤원남;정진택
    • 유체기계공업학회:학술대회논문집
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    • 유체기계공업학회 2003년도 유체기계 연구개발 발표회 논문집
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    • pp.514-519
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    • 2003
  • The objective of this study is to document the secondary flow and the total pressure loss distribution in the contoured endwall installed linear turbine nozzle guide vane cascade passage and to propose an appropriate contraction ratio of the contoured endwall which shows the best loss reduction among the simulated cases. In this study, three different contraction ratio of contoured endwalls have been tested. This study was performed by experimental method and when the contoured endwall has the contraction ratio of 0.17 on exit height the results showed the best loss reduction.

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수치 해석을 이용한 감압 회류 수조 설계 (Depressurized Circulating Water Channel Design Using CFD)

  • 부경태;조희상;신수철
    • 대한조선학회논문집
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    • 제40권4호
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    • pp.22-29
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    • 2003
  • New high-speed depressurized circulating water channel was designed by using the CFD code. Flow in the channel has free surface and pressure in the test section can be depressed. In this study, Flow separation and bubble occurrence were considered in designing the contraction nozzle shape for better flow uniformity Tn the test section. To supplement velocity defect due to the free surface, nozzle injection system more effective in high-speed flow was installed instead of drum system. Necessary power and injection techniques were proposed. And guide vane arrangement was analyzed to reduce the flow resistance and keep quiet free surface from ´surging´. Wave absorber was devised to reduce the wave resistance and to prevent the entrainment of air to the diffuser.

노즐 축소부 수렴각이 고속 광섬유 피복유동에 미치는 영향 (EFFECTS OF CONVERGENT ANGLE OF NOZZLE CONTRACTION ON HIGH-SPEED OPTICAL FIBER COATING FLOW)

  • 박신;김경진;곽호상
    • 한국전산유체공학회지
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    • 제21권4호
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    • pp.11-18
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    • 2016
  • A numerical study is conducted on the optical fiber coating flow in a primary coating nozzle consisting of three major parts: a resin chamber, a contraction and a coating die of small diameter. The flow is driven by the optical fiber penetrating the center of the nozzle at a high speed. The axisymmetric two-dimensional flow and heat transfer induced by viscous heating are examined based on the laminar flow assumption. Numerical experiments are performed with varying the convergent angle of nozzle contraction and the optical fiber drawing speed. The numerical results show that for high drawing speed greater than 30 m/s, there is a transition in the essential flow features depending on the convergent angle. For a large convergent angle greater than $30^{\circ}$, unfavorable multicellular flow structures are monitored, which could be associated with wall boundary-layer separation. In the regime of small convergent angle, as the angle increases, the highest resin temperature at the exit of die and the coating thickness decrease but the sensitivity of coating thickness on drawing speed and the maximum shear strain of resin on the optical fiber increase. The effects of the convergent angle are discussed in view of compromise searching for an appropriate angle for high-speed optical fiber coating.

연료노즐의 내부유동 및 외부분무 특성 (Characteristics of Internal Flow and Fuel Spray in a Fuel Nozzle Orifice)

  • 홍성태;박장혁;구자예
    • 한국분무공학회지
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    • 제1권1호
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    • pp.76-84
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    • 1996
  • The nozzle geometry and up-stream inject ion condition affect the characteristics of flow inside the nozzle. such as turbulence and cavitation bubbles. Flow details in fuel nozzle orifice with sudden contraction of cross sectional area have been investigated both experimentally and numerically. The measurements of velocities of internal flow in a scaled-up nozzle with different length to diameter rat io(L/d) were made by laser Doppler velocimetry in order to clarify the effect of internal flow on the characteristics of fuel spray. Mean and fluctuating velocities and discharge coefficients were obtained at various Reynolds numbers. The turbulent intensity and turbulence kinetic energy in a sharp inlet nozzle were higher than that in a round inlet nozzle. Calculations were also performed for the same nozzles as scaled-up experimental nozzles using the SIMPLE algorithm. External spray behavior under different nozzle geometry and up-stream flow conditions using Doppler technique and visualization technique were also observed.

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장방형 충돌수분류 냉각계의 국소열전달에 관한 연구 (A study on the local heat transfer in rectangular impinging water jet cooling system)

  • 이종수;엄기찬;최국광
    • 대한기계학회논문집B
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    • 제20권4호
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    • pp.1395-1405
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    • 1996
  • The purpose of this experimental research is to investigate the local heat transfer characteristics in the upward free water jet impinged on a downward flat plate of uniform heat flux. The inner shape of rectangular nozzle used was sine curve type and its contraction ratio of inlet to outlet area was five. Experimental parameters considered were Reynolds number, nozzle exit-flat plate distance, and level of supplementary water. Local Nusselt number was influenced by Reynolds number, Prandtl number, supplementary water level, and distance between the nozzle exit and flat plate. Within the impingement region, the Nusselt number has a maximum value on the nozzle center axis and decreases monotonically outward from center. Outside of the impingement region, on the other hand, the Nusselt number has a secondary peak near the position where the distance from nozzle center reaches four times the nozzle width. However if nozzle exit velocity exceeds 6.2 m/s, the secondary peak appears also in the impingement region. The empirical equation for the stagnation heat transfer is a function of Prandtl, Reynolds, and axial distance from the nozzle exit. The optimum level of supplementary water to augment the heat transfer rate at stagnation point was found to be twice the nozzle width.

부상화염에서 예혼합화염과 삼지화염의 천이적 거동(I) (A Transitional Behavior of a Premixed Flame and a Triple Flame in a Lifted Flame(I))

  • 장준영;박정;김태권
    • 대한기계학회논문집B
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    • 제29권3호
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    • pp.368-375
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    • 2005
  • We have presented characteristics of a transitional behavior from a premixed flame to a triple flame in a lifted flame according to the change of equivalence ratio. The experimental apparatus consisted of a slot burner and a contraction nozzle for a lifted flame. As concentration difference of the both side of slot burner increases, the shape of flame changed from a premixed flame to a triple flame, and the liftoff height decreased to the minimum value and then increased again. Around this minimum point, it is confirmed a transition regime from premixed flame to triple flame. Consequently, the experimental results of the liftoff height, flame curvature, and luminescence intensity showed that the stabilized laminar lifted flame regime is categorized by regimes of premixed flame, triple flame and critical flame.

Fluidic 유량계의 기하학적 변수가 유동률에 미치는 영향 (Effects of geometric parameters of fluidic flow meter on flow rate)

  • 박경암;윤기영;유성연
    • 대한기계학회논문집B
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    • 제21권12호
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    • pp.1608-1614
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    • 1997
  • The fluidic flow meter detects the gas flow rate based on the principle of fluidic oscillation instead of the conventional displacement method. It has many merits: wide rangeability, no moving mechanical parts and calibration insensitive to physical properties of fluids. The width of nozzle, size of oscillation chamber, size of target, width of outlet are tested to obtain the effects of jet oscillation on the fluidic flow meter. As the width of nozzle is too wide compared with the size of target, jet oscillation is unstable. The oscillation frequency decreases as the distance between the nozzle and target increases and also as the distance between target and outlet contraction increases. Two different vortexes exist in the front and the rear regions of the target, and they affect the oscillation frequency. The outlet contraction is very important, because the feedback flow is generated by the blocking of the flow. As the width of outlet increases, the jet oscillation frequency decreases. The linearity of this tested flow meter is quite good.